Hello, dive OP here. This can be a tricky one as both parties have potential to lose out if an effective cancellation policy is not in place. I appreciate this may not work for everyone, as there will be regional differences, but if it helps anyone, here's how we operate...
We sell trips and courses (and not just diving - rock climbing, abseiling, cliff jumping, watersports, boat charters etc too) online, over the phone and in person to walk ins. If a customer wishes to book we ask for a deposit - nothing huge, but enough to deter no shows. Walk in customers pay this in cash, phone and internet bookers are sent an online invoice to their email address, which they have the option of paying either via Paypal, or credit card but still using the Paypal site as a host. This way the customers details remain secure, and they know there is no way of us using them to take more money without their permission. Whether booking in person or electronically they are shown a copy of our refund and cancellation policy, and must sign - or tick an electronic check box - that they agree to it. Here's how it reads:
"Deposits
A deposit per person of 500THB for activities and 2500THB for courses is required at the time of booking. The balance of payment is due on the day of the adventure.
Refunds
Refunds are available on deposits for the following conditions only:
1) Goodtime Adventures is unable to offer either the adventure booked or a suitable alternative (activity or date), for example due to weather conditions or staff illness
2) The customer is unable to take part in the booked adventure due to illness or injury, provided Goodtime Adventures is notified 24 hours before the scheduled departure time of the trip
If you need to contact us to change or reschedule a booking, please be aware that our office opening hours are 08.30am-19.00pm.
Bad weather, staff illness/injury & equipment failure
1) If no part of an adventure is possible and a mutually agreed time to reschedule is not possible, the customer is entitled to a full refund of monies paid including the deposit
2) If up to half an adventure is possible the customer agrees to pay half price
3) If over half an adventure is possible the customer agrees to pay the full price
If Goodtime Adventures has made the full adventure available but the customer chooses not to participate in any or all parts, the customer is liable for full payment at Goodtime Adventures’ discretion."
Like I said its not foolproof in all locations, but it means we never cancel trips on remaining customers who no show/cancel last minute, as their deposit goes towards covering boat/equipment/staffing costs etc anyway. We can be somewhat flexible on this though - for a regular customer for whom last minute cancellation is an anomaly, there is some wiggle room. For new customers who hedge their bets and ditch us for another company - no chance!