I have been to Velorusion (talked to owner, an italian ??) and saw impressive workshop in basement. But I only wanted a spare rear wheel. … seemed like a good outfit.
Another Strida dealer in London is Bikefix, lambs conduit st. (now, they Should fix it 
).
If I were you, i’d study all the manuals and stuff here and DIY … there is not much on these bikes to fix … and … I’d contact Strida europe with this story - I am sure they would want to
a) hear, and
b) help - they will have more experience with Strida, in Europe (apparently there are many, many more sold there).
FWIW …
www.strida.co.uk
rik@strida.nl
jasmijn@vanmoof.com
Wibautstraat 129-5th floor
1091 GL Amsterdam
The Netherlands
T: +31 - (0)20-3307401
F: +31 - (0)20-3305132