I think I may be wrong but I think you can buy crysta with a RIXTY card which you can setup at rixty.com then top up your account with your mastercard for the amount ya wish then when ya goto buy crysta at square you choose pay with rixty option it will have ya login to rixty and will deduct that amount your choosing from your rixty balance...its a bit of back and forth but it w orks and as you spend money filling your rixty you get points with them and accrue enough and they give you free rixty cards as well. Very popular alternative way around issues like that. Just a suggestion.