Changing ISP

[Sasso1]

I recently changed my ISP and received the Migration Authorisation Code (MAC) from the old provider.
I completed the aplication form on-line but did not find a question asking for the MAC.
Approached the new provider who advised me that the code was not necessary.
I am now having problems with the old provider who say that because the new ISP did not notify them of the code I am still a customer of theirs even though I had notified them by telephone.
My new ISP (Tiscali) do not answer my e-mails & unable to make contact by telephone.
Any advice would be helpful. Thanks
sasso1