slipping straps

I bought 2 bras from the store at Conduit Street about a year,ago on a trip with a friend who wears their bras all the time. As it was my first experience of the store I wanted to treat myself to something pretty rather than functional. The fitting and staff were lovely but no lovelier than my long term experiences at John Lewis' service. The bras looked wonderful and felt very comfortable. I am sensitive to some fabrics but these didn't scratch or cause irritation. I walked out feeling wonderful and pleased with my £200 purchase, but that soon changed. The bras gave me a lovely shape so I love the style BUT the straps slip constantly so I have to adjust them regularly throughout the day. This makes me feel very uncomfortable, unsupported and embarrassed. In addition to the slippage, the stitching under the arm on one of the bras became unravelled after only a few wears. Unfortunately, I haven't been back to the store to follow these issues up, which is negligent on my behalf and means that I have no experience of their customer service. However, I will not be shopping with Rigby and Peller again and I continue to shop at John Lewis for my bras and receive great service, measuring and product reliability.