If a clinic offers you a 500$ refund a few days after surgery that means there is something wrong or shady going on, don't go back again for a follow up even if they offer you one for free, I know it's frustrating but you have to wait at least 6 to 8 months now to see any results and based on that make your decision on where to go next, good thing it was a small procedure and if you counted way less than 1500 that's even better, I have seen guys that had huge sessions that were butchered and there is nothing they can do about it now. Don't call the clinic now, wait 6 months now, results might surprise you and if you don't get the result that was advertised try asking for a full refund and just move on completely from that clinic. Mistakes happen sometimes, I have been in this situation before, I went to a bad place and lost a huge number of grafts and that's something that I can't get back, luckily in your case it was a small procedure, what matter now is that the grafts that were planted survive, you can do a follow up procedure with another skilled surgeon that will work on the density, you are going be fine.