I don't use square nor does a quick search show a phone number for them. In does though show a lot of unhappy customers not able to find a phone number to square. Sure seems like if nothing else an opportunity for them to fix perceptions and help people.

Be somewhat thankful you aren't with Paypal, that 90 days would be 6 months and there is little to nothing you can do about it. From what I understand technically, there is a 6 month window where credit card transactions can be challenged (at least in some cases), so many times Paypal et al will hold money for all or a portion of that period if your business is deemed high risk.

You don't mention what your business is or what it is you do, so it is hard to judge why they consider you high risk. But good luck trying to get ahold of Square other than through support forms or email from the way it looks.