Returned an item to a shop. i'd like a refund but i'm forced to exchange the item. [England]

i visited a climbing shop a while ago to buy shoes. on the way out i tried out a climbing harness. i decided to take it. a few days later i tried on the harness again in clothes i would climb in and i was really uncomfortable, enough to not want to climb in it.
i emailed the store and asked if i could return the harness. they replied and said yes.

my partner was going to be around the area, so i gave her the harness to return. she told me they were not going to refund me. i emailed for more info and they said they do not take back safety equipment. i explained that i was ages on the shop, hesitant with shoes and asked if i could return if i changed my mind. they said yes. then i got a harness quickly before leaving and didn't know there was an exception to that.

the owner said he would take back the harness since it was within the week, providing it had the tags and was new. it was. and i could come by to try something else.

life has been busy and i haven't had a chance to travel across the country to visit this shop. ive emailed about other items and things i could buy but there isn't anything else i want. i'd prefer a refund at this point.

i've tried having a search today and i can't really tell if i'm entiteld to one since the shop took the item back. or if they are being generous in only allowing an exchange on something else.