Thanks for that. I was just worried that I was being taken for a ride

I would happily pay if the architect had seen his error and updated with a quote from the builder. But that is not what happened. The builders were digging the founds and seen that the drainage layout won't work as the ground was going up. The next day the contractor and the architect showed up and told us that the drainage has to redesigned via a different route and we need to agree then and there for the cost of rerouting the drainage. They were forceful and made us agree to it. It never sat right with me. Because we had agreed then and there, we had to pay out for it.

The architect designed the drainage wrong, i.e he didn't take into account that the ground was rising. The builders seen this and flagged and another way of providing the drainage was discussed with 1m dropped required. This was put to us at 1100 pounds on top of the original tender. I would like to know who should be footing the bill. Is it always the customer even though it is not some unforseen issue? Please advice Thanks