No boarding for wheelchair users

On the return I was going to use the DLR at Tower Gateway; however I was informed that this had shut so it was suggested that I use Tower Hill tube - useless really as this is inaccessible to wheelchair users. So I proceeded to walk back arriving back at 14.05pm - miserable and very wet. I walked through the ticket gate and staff shouted out to the platform staff that a ramp was needed. I proceeded to the platform where the staff were still letting people onto the train and I politely asked him for a ramp for me to board. Totally ignoring me, he blew his whistle for the doors to shut and the train to go. Rather perplexed I asked "Why did you let the train go? you let everyone else on". And his answer was, "because you use a wheelchair and it would take a lot more time".