Paid up letter

I paid up my account on the 2nd of December, I was advised that it would take 3 working days for me to get my paid up letter. Today is day 9!! I've been following up with the call centre but no luck still, there is never a team leader or manager to speak to either and I advised numerous times that I need the letter as another company is awaiting my details. I've sent emails, called and even went to the closest branch and still nothing! This is not the way to treat loyal customers - I've never missed a payment and was always happy to hear from the company. This treatment is uncalled for and unfair!