In the UK, most accountants operate a model in which they charge an annual or monthly fee and that will include specified task throughout the year. My accountant charges me £700/yr and for that I get my accounts prepared company tax return submitted and a few other things. But because he gets this guaranteed income from me, if I fire off some emails with some questions throughout the year, he's happy to answer at no charge. If you were getting a regular monthly payment from your client, you'd feel the same.
Also to touch on the minimum fee issue, my accountant bills £100/hr, and if I do ask him to do something that's out of scope of what he feels is covered by my yearly payment, I would always expect the cost to be at least £100. There's no fanfare, no bold statements about what a hassle it is to do these extra jobs for me. And even if it somehow takes him less than an hour, I would still expect him to charge me a minimum of £100. He doesn't bill in minutes and I'm not naive enough to think that even the simplest job can be done in 5 minutes. It's just a reasonable expectation, so personally I think it's fine if you just bill in hours and I think your clients will be fine with it to.
What I don't believe is that many clients are going to accept a 3 hour minimum, because that doesn't sound reasonable at all, it's quite an aggressive stance.
Me sitting in front of my desk and being available for support, with all the business expenses that involves (salary, insurance, office costs, computers, internet etc etc) is not exactly free if you add it all up and should be worth something. The alternative would be taking on so much work that I would have to say no to doing updates.
That doesn't make much sense to me. If you had no work, you'd still be racking up all those expenses. Also I think you need to start viewing the update requests as an opportunity, not a burden.
On the other hand, my local car repair shop wouldn't send me an invoice for prepaid hours in case I ever need my car repaired.
Maybe not 'Honest John's Garage' but all the local dealerships near me offer a monthly package that includes a specified number of repairs, parts, annual service, health check etc.
I guess the key term here is "support agreements" and "response times" because when I get overwhelmed I don't always respond to emails and then I get two or three (angry) emails requesting the same things and that adds to my stress levels and this is bad customer service, regardless.
Well, that's is a very easy problem to solve. You need to structure your workday better - back to my poor accountant again, he goes to work at 7.30am and spends the next 90 minutes dealing with all the crap, including emails. At 3pm, he sets aside 30 minutes to respond to the additional emails that he's received throughout the day. The key is to respond in a timely manner, even if it's 'Hi John, just to let you know I got your email and will get back to you in more detail first thing tomorrow'.
You also need to ensure that your clients understand you do not work for them exclusively, you are not an employee, you have many other clients and projects to deal with. If a client is determined to adopt a pay-as-you-go model, they have to accept they will not get the same priority as the client who pays a regular update and maintenance fee. Make a point of holding back - if you get the call on Friday for example - 'yes, I can do that for you, no problem, I'll get that done next Wednesday.' If the client is not impressed, politely remind them that you deal with clients on priority support packages first. No big drama, just matter of fact.
Once again back to my accountant, at no point did he ever offer me a 'pay as you go' model, from the beginning it was all about the annual contract. It might be worth you considering this model, because all in all, it's a lot less stressful for everyone.
Also,I place a very high value on recurring business and repeat clients and this is why I don't mind doing silly little updates. At least in theory, the problem is finding the time. But if I could allocate enough time to do them, it wouldn't be a problem.
Well they are only silly to you, pretty sure your client thinks they are important As such, they should be receptive to the benefits of paying for a monthly support package (IMO!). If you have xx clients on a x hour monthly package, you can at least get a good idea how much of your time to set aside every month for these priority requests. It's all about structuring your time, especially if you do everything on your own.