Old Mutual refuses to compensate

I have had a policy with Old Mutual for over 20 years. The debit was being taken directly from my gross income and all premiums were honoured. When going for an early pension, I returned the company phone but my new number had been given to my former boss for any communication that I may be reached on that number. There was no communication from Old Mutual via telephone or via post as this was the method I used to receive all my communication. 10 Months later which was in July 2020 I received a mail from them advising the policy had been cancelled due to non payment and the letter was dated February 2020 but I believe due to Covid-19 there was a delay at the post office. When trying to communicate via email, was advised the email address is not the account numbers but when I provided the telephone number for them to call me they also refused but gave me their telephone number instead. I phoned the number and was advised that they are working remotely and keep on holding until the line cuts. I feel very disappointed because for more than 20 years I've had this policy but to receive such treatment tells me allot about this company.