I am sorry to hear that the train was well occupied.
Generally speaking, Swiss railways offer walk-on services, tickets do not guarantee a seat but transportation. Therefore, tickets do not come with a seat assignment and you can take any seat that is vacant. In the unlikely event when all seats are taken, you might have to stand in the aisle until the next station, where some people leave. There is, nevertheless, no refund for not having had a seat.
Working as a ticket conductor, I can tell you that there are always seats left, either in the coaches in the front or in the back of the train. Most people do board the train in the center coaches and those get busy quickly, leaving the impression that the entire trains is fully booked.
Point-to-point tickets are valid for any connection. If a train is well occupied, you can simply take the next train.
If you are unhappy with my answer, please see the refund request form here. Only SBB can tell you if a refund is justified in your specific situation: