Would you do this (returning stuff)?

[itstheyearzero]

I needed a pair of black 7/8 trousers for work about 6 weeks ago, so I went into New Look and spotted quite a nice pair. I'm always a size 12 in New Look, however, the 12's looked really small so I bought a size 14. I didn't have time to try them on, but thought they'd be OK based on past purchases. Anyway, I hung them up in my wardrobe, but didn't wear them due to the fact that I've been mainly working from home since then. I thought I'd wear them today, but when I put them on I realised they are far too tight round my waist, uncomfortably tight :(. Now I can't find the receipt anywhere. Would it be terrible of me to go and buy a size 16, then use the receipt to return the size 14's?
The trousers still have all the tags on......

They will know the receipt isn't for the 14's as the codes won't match. Can't you just take the 14's back and exchange for the 16?

They would exchange them for the 16s without a receipt. That's only really for redundant.

Why would you not just take the 14s back without the receipt and ask to exchange them for the 16s? Most stores are happy to exchange without a reciept. In fact I bought a bikini from Next a while ago for my hol but never wore it as the weather was too rubbish so wanted to take it back (am BFing so bought the size that fits now-I know when I stop I'llchange size). Didn't have receipt so fully expected to be given exchange only but they scanned the tags and now have a fancy new system that could tell them where I bought it, how much I paid and which card I used! So got given a full refund, no quibbles at all. (Although choosing to ignore possibility of storing card details!!)

Oh really, I didn't think they would entertain the idea of taking them back without receipt!