Sorry if this is a duplicate, I cannot see my post after editing it to make the fare table more readable.
I have now tried a similar journey with Contactless but I seem to still have the same issue.
My understanding from reading the TfL website and this video from Geoff Marshall is that Contactless (and Adult rate Oyster) will give you the best value of various combinations of caps and individual fares.
The fare Zone 1-3 Cap is £10.50 and the fare from West Ealing (Zone 3) to Windsor & Eaton Central is £5.20 meaning the total for the day should have been no more than £20.90, but I was charged £22.30
Day............Journey....................................................Charge (GBP)..Capped
Saturday.......West Silvertown DLR Station to Windsor & Eton Central..-10.80........N
Saturday.......Windsor & Eton Central to North Greenwich..............-10.60........N
Saturday.......North Greenwich to Plaistow..................................0.90........YI am unsure of how or why it is calculating this fare.