URGENT!!! Was I Scammed???

Please I'm really sorry this post is going to be a bit long. I went to a supermarket today to get stuff. I bought stuff worth #1040 and paid using POS. My phone was off as at the time of payment. When I got home and charged my phone, I immediately saw alerts.. One showing a debit alert of #20,000 and another showing a debit alert of #1,040. Both transactions were done using POS.. I was shocked because I never bought anything worth #20,000... And the #20,000 credit alert showed that the POS was used in Ikeja, Lagos...but the supermarket I bought things at is in Ibadan. My question now is, can I get my #20,000 back or have I been permanently scammed?embarassed Or has this ever happened to anybody??