Books sent back not credited properly. No customer service

I sent back 4 handyman books, two at a time all with the correct mailing sticker and two of these books were not properly credited to my account.  I  even over paid 28.00.  I have been hounded for three years in spite of registered letters sent to the company detailing the problem.  There has been  no  appropriate responce from them other  than an obnoious coolection service which has also been sent letters and told aboutthe problem numerous times. I have also told customer service  at least 4 times to  stop sending the magazine, to no avail. This is a nightmare company to deal with, no customer service whatsoever. Also the promiced review of tools has been a total scam.