I would never use a different lamp to cure other gels as you’re not supposed to, I only got the mini one as that was what we needed when I did the training, I just do all the fingers and do the thumbs together
Get them to pull down their knickers to just below where they want waxed, get the edge straight and kind of use that as a guide line.
If you are using strip wax you can also use the edge of the strip as a guide line
I’m not a hairdresser but it looks awful after being cut! Maybe she is only messaging you for a refund because the other person hasn’t cut it very well and she needs new extensions now?
I wouldn’t refund her unless the hair was faulty
Just my thoughts