Review of Mainland Taxis Ltd

I ended up in a Mainland taxi from Christchurch Airport last night heading home. I travel fairly often so am very aware of a 'normal' taxi fare to and from my house to the airport. On arriving home I glanced at the meter to see a fare on the high side of normal straight off the bat. I didn't think too much of it as taxis these days always seem to tack an extra $15 on for trips from the airport and blame it on airport taxes, and handed over my Visa card. The taxi driver proceeded to use the payWave process, but just before he did I saw on the payment screen a cost of $44.70 when the meter clearly read $42.70.
The transaction went through and I asked for a copy of the receipt... He um'd and paused. Then said "payWave doesn't give receipts..." I questioned this as I had never heard of this before and asked if the transaction had gone through because I needed a receipt and he said yes, all went through fine, then suggested that he would have used the other machine if he knew I needed a receipt!? Then assured me that my bank statement would read $42.70 as on the meter.
Not in the mood for an argurement I got out but checked this as soon as I stepped into the house and as I had suspected, $44.70 was charged!
Fraud... Or honest mistake.....?..
All I can say is, be aware of your transaction amounts before handing over your cards for payWave!!! It is very easy to end up with a situation like this and I wonder how many times this has happened... Mistake or not.