OH is going to sew the hook back on for me and we are going to trip off the loose threads.
Looks like they are just superficial, and to be honest I'm not convinced that another return they send me out won't have threads hanging off it/something else wrong with it. The hook fastening at the back is ridiculous and a really bad design, so was likely to get loose at some point anyway as probably not attached particularly well, so at least I know that OH will do a decent job of securing it
The 10 I ordered has a white patch under the arm that I hadn't initially noticed either so sod it, going to keep the 8, sort it as best I can and wear the bloody thing tomorrow!
Tell me I'm doing the right thing....please?!