A test could cost as little as £25 if he can arrange getting it to the tester & collecting it.
Hydro testing is a test of the cylinder and not the regulator and some places require you to remove the regulator before it goes to test.
What he could do is arrange testing, hand it over with the old regulator and give instructions that the regulator does not get refitted.
That way he cannot lose the new regulator, gets the old one removed by someone with an idea of what they are doiing with minimum chance of more damage such as the threads.
If it comes back fine then he has not lost out.
So he risked £70 on an untested cylinder, then got some money back on the regulator
So you paid £70 for the tank
Got a refund to cover a regulator
£49.99 for the reg
And will pay £35 for a retest
Correct me if I'm wrong ppl but can't you pick up a brand new bottle for that price. Ok you might of got a refund for the reg but it has to pass like lump said otherwise you won't get anything back including the £49 reg
Kids these days lol