I offer support contracts to my clients who I create websites for.

I have 3 support packages and each one offers a different amount of allotted support time per month for a set fee per month.

I have one client who before the first contract was signed (a year ago) asked that any unused support time be transferred to the following month.

I said that this was not possible and drew comparison with UK mobile phone contracts where any unused minutes in a month are lost.

Now the client is looking to renew the contract after the first year and the client has asked that at the end of each month any unused support time is used up by us by proactively finding out what improvements can be made on the client's website and then making the improvements. The downside of this is that you only find this out at the end of the month.

Do you think this is a reasonable request? Or do you have any suggestions on the best way to deal with this and left over support time?