You need to call payment management.
Details on this link Guide: Coronavirus Community Help and Support
Don't take anything for granted. You do not want any mistakes
regarding this type of letter as it could escalate, if not properly
and officially dealt with.
I can only add that if it were me I would reply to the letter you have
saying the date you paid your account and from where etc. so that
it is in writing, send by Recorded Delivery to the address on the letter.
Then this will be in the pipe line and is a positive written reply.
All other methods rely upon Customer Services being able to do
their job in these difficult and uncertain times.
As stated do not use Live Chat for this ~ my opinion of Live Chat is they are ok
for the odd light-weight problem.
Good Luck and Best wishes TallTrees
Edited to say ~ Make copies of all the correspondence
That can often happen that a letter arrives well after it is dated. However it does not change the necessity to make absolutely sure that you communicate to O2 that you have paid the money outstanding mentioned on the enforcement letter.
The enforcement letter empowers a company to proceed to a court order and enforce payment through retrieving your goods in lieu of payment.
It would be wise to advise o2 in writing using the details and address on the letter as this is proof you made contact and details that you have paid.
It seems simple to use the phone for this and it could be ok.... the choice is obviously yours.
However there is "many a slip between cup and lip"
Good luck and best wishes TallTrees