There are companies specialising in helping to obtain residence and work permits - I won't plug them here because they are easily found on the internet. The usual fee appears to be around 3000 CHF.
Such firms don't appear to do anything that could not be done on your own if you're prepared to do the homework but they could be a comfort zone for some. They cannot, of course, create a magic permit so if you don't qualify you are probably wasting money.
In this case the missing part for me is the contract. It could be argued that the emails consitute a contract but whether it would be worth fighting this in court is debateable. If you gave a clear instruction to him not to proceed with the translation (3500 CHF? How big was it, my better half would do it for 75 CHF a page

) and have evidence to that effect then remind him of that fact and that you will not pay the invoice. I do not think he could win an action on this - but then I'm not a lawyer

.