I sent a couple of bras back a while ago and they never arrived. DP had taken them to the PO for me and didn't get a receipt, so I gave him a massive bollocking and wrote it off - they were on sale so not ££. But now I have sent another lot back, total cost over £70. DP says PO said they don't do receipts as it's 2nd class post (??). He sent them a week ago and they've not acknowledged receipt yet. I'll give it a few more days before panicking, but I'll be seriously annoyed if it happens again.
Bra stop is free returns so the post office should give you a proof of postage as standard. I've shopped with them loads and never had a problem with things going missing or refunds. I'd give them a call as they've always been v helpful in the past.
I called them last time and they said without a receipt there was nothing they could do. Gah - I thought after last time DP would insist on proof of postage but they told him it wasn't needed/they didn't do it. They gave him a receipt for the ASOS parcel.