PLEASE SORT IT OUT

Just when i thought i was covered by thee best insurance company, when i initally took my car insurance cover i was given a voucher which i did redeem for a magazine subscription and was told to expect first delivery in 6 weeks, its over 4 months and nothing so i call the call center and no one seems to know anything all they do is take my number and offer to call me back after holding for 20minutes and they still dont bother calling me. I have tried calling again and the same thing happens what am i to do to have this resolved???