We stayed in a very pleasant large dual aspect room, with a great view over the city. we couldn't fault the room.
On arrival we were told we had prepaid (which we had), would we like breakfast - we said NO, and told that the car park was unfortunately full. Fair enough. We parked elsewhere.

However on receiving our express check out bill, we had been charged for parking for 2 nights (which we hadn't used as it was full) and for breakfast ( which we hadn't had as we had been out for breakfast with our son who is at Uni in Cardiff).
We had also been charged for our 2nd night stay again.
The complication arose because we had booked and paid for the the 2 nights separately and rung the hotel in advance to ensure we only had one room for the 2 nights. Their system couldn't cope with this.

When querying the bill, when we said we had not used the car park, we were accusingly asked where we had parked. How dare they. They need a system that records use. We were told that as we had put our car registration number on the booking that we would automatically be charged. HOW RIDICULOUS.
They regarded taking this off our bill as doing us a favour. It should not have been charged at all.
Breakfast the same they removed the charge, again as if doing us a favour. Again why were we charged in the first place, we never set foot in the restaurant.

And as for the charge for the 2nd night. They told my husband that they had cancelled the 2nd night booking and amended our first night booking to be 2 nights - expected us to pay an additional £20 and the room fee, which after an argument they agreed to charge the original amount.
We assumed this was because they had refunded out 2nd night fee back onto our credit card. So we paid. However no such refund was done,
Before leaving we checked with our credit card provider , found no such refund ,showed the reception staff our online credit card statement showing no refund, but 2 separate payments to Mercure, but because they couldn't find a payment on their system, they didn't believe us. They even suggested it was because we had booked through laterooms, when in fact we had booked direct with Accor Hotels. I have never been treated this way by a hotel before.
They suggested we leave it with them to investigate with their accounts department when they were quieter. They would then contact us later on ( when?) and refund us if they found the payment. It all seemed to be our fault. So we as customers didn't matter as they had other guests to see too?
3 hours later they had done no such thing and because I was hanging around reception, obviously less than impressed, whilst a large queue was forming they did eventually refund us. We wasted over an hour sorting this out.The manager was "out", and despite arriving back did not come and see us.

We expressed to the reception staff that less vigilant customers may leave in a hurry, and pay for things that they shouldn't. They assured us that no one was ever charged for things they didn't use. From what we have seen we cannot believe this ,as the systems in place are absolutely hopeless. It is such a shame as the hotel itself was very nice, but I'm sure we'll be able to find another one in Cardiff with a better attitude towards its guests.
Having had a great weekend we left feeling very disappointed with the attitude of the hotel.
One other thing the pool is freezing cold.