Retrieve phone number from July 2009 Bill

[Anonymous]

Hello, 

I need to retrieve a phone number which I do not have saved on my phone or SIM card and which I last contacted in July 2009. The latest bill I can access online is 2010.

Has anybody been able to retrieve old data like this? I have called customer services but they could only access the same bills as me. Does a written request for information help here?

Thanks for your help.

[Liquid]

Problem is data is only legally required to be kept for 3 years when not in use.

Since the bill is so old they have probally deleted it:(

Is there no other way to retrieve the number you need?