i think he meant slots on his equipment for chips?
IF that is the case then the 6th slot is 80 gems and the 7th is 160 (=240) so it cant be that he opened 2 at once. but what happens to me sometimes is that its asking me if i really want to spend the gems on the chip (autobuyfunction or something to match the current chip) and you may have disabled it at some point, however that cant be it either because a lv 3 chip is 100 and a lv4 chip is 300.
opening multiple slots cant be either since that would add to 151. so maybe you have opened some minor slots and forgot about it or spent your gems on something else.
in either event the forum is the wrong place for it and you should contact customer service. since its most likely stanley who will take care of you, you should include a date and a timeframe when it happened and you will get back a list of all gems earned and spent within that timeframe.