Determining SLA times when SR type changes in Service Request(SR)

Hello,

 I create a SR with a response time of 1 day and a resolution time of 5 days. The type is 'Complaint'.

 I have another SR type called 'Pay Query' which has a response time of 4 hrs and a resolution time of 8 days.

 The next day after creating the SR I change the type to 'Pay Query'.

I know the SLA times are recalculated when the SR type is changed, but on what date is the calculation based?

Is there a way to recalculate from the date of type-switch?

Thanks

Allin