Extremely Bad Service !!!

I purchased some denims from the Levi factory Store in Kenilworth and on my third wear I discovered that the zipper came loose. I called the store and explain the situation and ask what could be done in a case like this and the sales agent advised me to bring in the Jeans so that it can be sent away for assessment. I did as was advised and was told that I would be contacted to let me know if they will replace the item. After two weeks of waiting on a response I contacted the store and was told that they have a problem with courier service and that the denims was only sent away that same day and that they have my details and will contact me with feedback. Another two weeks has gone past and I'm still waiting on someone to contact me. The reason why I invested in some Levi denims is so that I can have a long wear out of it but it seems it is no longer the case as I find that the quality of these denims in my opinion is not really that great and the service seems to be even more pathetic. You don't just take someone's hard earned money and then just mess them around. Can I just please just have some feedback on my returned item?