Avis Poor Service

I made a booking in February 2019 for January 2020, booking was confirmed. Today I edited the booking and got an email saying it was modified then an email came through saying booking was cancelled. I called immediately to reinstate the booking and they would not help me reinstate the booking, rather I had to rebook under the new rate and all of a sudden the class of vehicle was no longer available. I find this service dispecable and not sure why they could not help me within 5 minutes of there error.