The services that were "turned off" can not just be "turned on". They were ordered and part of the previous owners package and were billed and supplied to that person.
No doubt there are other people who will be in the same situation as you. BT and all the other ISPs who use the Openreach network request that you are connected and Openreach carry out this request by allocating the next available appointment/work slot.
BT have no influence over when this takes place so unfortunately you will need to wait till the date supplied.