Santander Card Communication Problem

maddermanblue1_2

Hi all,
I'm at my wits end with Santander credit cards. My situation is this;
A few months ago I took signed up for an Outfit credit card with Santander as I thought it was a good deal as you get a good discount on clothes when you buy in store also you don't have to pay straight away.

A week later I got my Outfit credit card etc. A few days later I moved house, which prompt me to write to them to say I have changed address, I also asked them to send any outstanding payments statements.
On the back of the T&C it says I need to ring to change my address but I cannot as I am deaf, so I wrote to the address instead.

4 weeks later I heard nothing until the owners of my previous address kindly hand delivered my outfit letter which contained my statement (only one letter as I do everything else online and is paperless) The date of the statement was 24th April, it was delivered to me on the 13th May I had to pay by the 19th May, on the same day I promptly sent off a cheque to pay the balance off in full including a letter to say I had changed my address (again). Checked my banking online and the cheque had gone through on the 19th May (I thought phew, just in time!).

Heard nothing else from them until today, the owners of the previous address hand delivered the one letter again, you guessed it, the Outfitter card statement dated 24th May, I received it today (21st June) stating I need to pay a £12.00 late charge. Not happy as I thought the cheque was paid in time. They will not respond to my letters or change my address and stumped at the moment, and no I don't want to get someone else to phone for me, why should I?

I had enough, I now want to pay off the overpayment charge and close my account but fear writing a letter won't work.
Is there anything I can do without phoning them, there is no email address (also googled it to no avail), just a customer service phone number and an address.

Regards

Maddermanblue