Swiss International Air Lines review by Hw

I have flown more than 25 segments with Swiss in a 12 month period. I always select my seats in advance, for which I am being charged £ 30. I don't mind, because that gives me the opportunity to select the seat that I want. On at least 5 out of the 25 flights I was told either at the check-in or at the gate and once on the plane itself that my seat has been changed 'for operational' reasons, only to see somebody else seated in the seat that I have selected and paid for. I complained in writing that they should not charge me £ 30 for a seat that I did not select and not want and asked for a refund. Swiss refused a refund, although very clearly, I was paying for a service which they did not provide. I was assigned a seat by Swiss but I was being charged for 'selecting' a seat. I have had enough. I have made my last flight on Swiss, luckily there are plenty of other airlines flying the routes that I regularly fly.