internet providers

I changed my internet provider last week, they asked If I wanted to keep my phone number, I told them YES....today I tried to phone from my home line....it was not recognised, I had to phone my mobile from my home phone, that's when the new number showed on my mobile...they had changed my number even though I wanted to keep my old one, and didn't bother to let me know, why do they even bother to ask, this is the second time that this has happened. now I have to let all my contacts know the new number..