I’m far from saying that you cannot buy bras with 60 or 65 band in Zurich. But I havn’t seen them so far. If you know any shop that has them on stock, please let me know.
Buying underwear online is quite popular. All shops accept returns as long as all the tags are untouched and the bra was not used. However, if ordering from Switzerland you may have to pay the customs, that may make an unsuccessful try more expensive.
Below there is a list of some shops in UK that sell lingerie in a wide range of sizes:
BraStop.com Sales shop with last season offers.
Bravissimo Has traditional shops in: Aberdeen, Brighton, Cambridge, Chester, Glasgow, Leeds, London, Manchester, Newcastle, Nottingham, Oxford and Solihul.
Curves & Lace Has traditonal shop in Glasgow.
UnderCoverExperience Sales shop with last season offers.
Remember, that if you are looking for underwear in UK shops, you need to use UK sizes (30DD etc.)