Dispicable lack of customer concern

Booked tickets (Manchester- Lisbon - Manchester)8 months in advance, but still arrived at airport to be told we were on standby. Another passenger advised me she had checked in at airport previous day and was still on standby, so it is not due to how early you arrive.
We're told by unsympathetic check in staff that TAP deliberately ovbook their flights by at least 10% - on this occasion there were 21 standby passengers on an A319, as TAP hass rescheduled to use a smaller plane ( presumably to save them money).
Check in staff would not say when next flight back to Manchester would be ( turns out it would have been next day).
Cold, uncaring, Dispicable
Ack of customer care by an airline that does not value it's customers.
I WOULD NEVER, EVER FLY WITH TAP. I am a regular traveller and have never experienced treatment like this ( not even from the budget airlines.
Don't even think twice - DO NOT FLY WITH TAP - you work hard to earn your holiday money, so spend it with an airline that at least treats you with some respect.