So you're not currently on Infinity?
Can you post up a copy of the wholesale dsl checker please and I'll might able to find out a bit more for you.
I suspect what's happened is that your copper line has been moved to the new cabinet and has reduced your distance to the exchange, therefore the speed has increased.
If you want to say thanks for a helpful answer,please click on the Ratings star on the left-hand side If the the reply answers your question then please mark as ’Mark as Accepted Solution’