Business ProfileforAquatic Adventures and Paradise Watersports

I went on a parasailing adventure with my friend on 6/3, at the Long Beach location. I gave the beach attendant my card to pay for my portion of 100$ for the ride. My friend paid her portion with 100$ in cash. They did not provide a receipt. I noticed after it was all said and done, I was charged 200$ on my card. I contacted them, and they have no record of my friend paying cash. NONE. They can only say that I signed a waiver. After receiving the waiver, it goes over liability. Nothing in the waiver that says the payment i agree to pay. They wrote it in red ink after my friend and I signed the waiver. Even so, we agreed to pay 200$. NOT 300$ which the beach attendant collected. The manager will not give me money back. I have tried to communicate the level of frustration I have with this company for the lack of record keeping. How does a company not keep record of what was paid that day in cash or card. It's beyond ridiculous. How do they file for taxes? It's obvious, they are a shady business and someone is pocketing cash and not reporting it. Either way, they refuse to right their wrong and expect me to lose out on 100$.