Ok..

Well thats unfortunate - usually if they gave somesort of indication as to what fault code is was - then this may or could verify wether your chain is the cause here - usually the codes that do come up are related to cam/crank sensor / timing issues - sometimes it can be a faulty cam/crank sensors/wiring/plug connector and usually those are the first to check/clean up or replace even - too if those code do keep coming back then its posible the chain has stretched causing both sensor to run out of sync and obviously the ecu will see that- another way of known if the chain is at fault bar the obvious usual syptoms previously mentioned is to check the chain tensioner piston protusion.As you may know ESP is "electronic stability control" which works through varoius sensors inc steering/abs system - some almera's/tino had the switch for tuning off and on again .However if at all possible i would maybe get a "second opinion garage so to speak" on this before you go ahead with the expense on the chain.so least if their diagnoses or machine picks up the same codes and is backed up after having the car scanned again.then least you'll know what will need done to solve this one - you could try this website and see if there is any better garages locally http://www.goodgaragescheme.co.uk/