Laptop repair needed (Paris)

I'm looking for a reliable company to repair my laptop - I arrived in Paris 2 weeks ago and now my hard disk has failed. It's still under guarantee but I need someone who will be able to provide me with a reasonable quote that will be acceptable to the UK company who I bought the laptop from, and who I can then trust to carry out whatever repair is needed. Any recommendations?
Also I will need to buy a 16Gb USB stick to do a backup on before any work is done, is there anywhere in arrondissement 1/2/8 which is good for buying such things?
Thanks in advance!