The fact that it's been customised means that you can't reject it for no reason, but being non-functional is a pretty good reason.
Since they've already attempted and failed at one effort to repair, you have two rights under Consumer Rights Act 2015 section 24.
1) The right to an "appropriate" price reduction, i.e. the price of a new magazine, or them sending you one - it sounds like that's all that's wrong, unless gluing the stock plate on has affected the functionality.
2) A final right to reject, in which case they must refund the full amount that you paid, without reduction since it's within 6 months, and they must cover the costs of returning the goods to them.
They don't publish an email address, but you can screenshot the contact form, or text them to get a written record. Mention the failed attempt to repair, and be clear what remedy you want. Don't mention that it's been two toned, or get in a debate over it, that's not relevant.
When they tell you to do one, or ignore you, instruct your payment processor (credit / debit card or PayPal) to start a chargeback. Don't tell them that story above, or give any more than the bare minimum of information, they won't care. I wouldn't even say "airsoft gun" in case they get into a flap. Call it an item, or equipment, which it is. Just "ordered it, didn't work, was repaired but still doesn't work, seller won't refund, chargeback please and thank you".
Hi all i am new to airsoft and just want to say hi and maybe at some point get help with everything from decent BB.s to buying a rifle and turning it into a DMR as there is so much to choose from i get lost
Hi all i am new to airsoft and just want to say hi and maybe at some point get help with everything from decent BB.s to buying a rifle and turning it into a DMR as there is so much to choose from i get lost
Hi all i am new to airsoft and just want to say hi and maybe at some point get help with everything from decent BB.s to buying a rifle and turning it into a DMR as there is so much to choose from i get lost