Additional check in fee with Ryan Air

I have recently traveled from Portugal to London with Ryan Air and it was the worst experience ever... First they told me that online check -in is mandatory but only on arrival was I informed, then they told me to pay additional cost of EUR45 in order to get a ticket, keep in mind I bought this ticket weeks in advance and was not pleased to hear this, after paying all the additional fees they then told me I've been put on standby and only if there is space on the plain will I get a seat. So I waited stressfully at the check-in gates, I don't understand this as Ive bought my ticket weeks in advance, last I checked online check-in was an extra option for people wanting to skip the queue for faster boarding. Ive made a official complaint about this and have still heard no feedback from the call centre. Ryan Air has such bad customer support it is appalling. Ive been wronged and upset before one of the biggest meetings of my career and told that I might not make it due to the fact that Ryanair over books there airline, Ive flown with at least 15 different airline this year alone and have never heard of such a thing as mandatory check-in or over bookings. Ahg