You should ask a real lawyer if you should sue. Don't pay an up front fee to the lawyer, give them a percentage if they win. Since you didn't give security guards permission to search you, you could claim assult or sexual harassement, etc. Especially they were at fault, they won't be able to fight vigoriously in court. Security guards do not have specialy any police authority, Legally they are just like normal people, cannot even tough your body.
If you only want an apology, then write a letter to the general manager of the store. If no reply, write to ceo of the corporation.
If you only want an apology, then write a letter to the general manager of the store. If no reply, write to ceo of the corporation.