Lack of paid up letter!

They are so quick to call and threaten you to settle the *** yet take up to a minimum of 2 months prior to sending the paid up letter. Even after payment is made, they still call you and want you to settle your *** as though you have not done so yet. Then they promise to send the paid up letter but fail to do so and conveniently apologise for the inconvenience. This is unacceptable as we await the letter because we have already waited the 21 working days then they tell you to wait a further 21 working days!