No plus sized robes at the spa

First time posting here. I am going to a new high end spa in February. I inquired about bigger robes. The largest they have is extra large and they insist it will fit. I'm a 3X so obviously that's not happening. Should I push them to order some plus sized robes since I obviously won't be the first or last person who needs a robe that fits? I ordered one but will return it if I can get them to provide one.