If you dont have the equipment you cant do the job.
Van and roof racks are not mean to be stood on and actually break all wahr, hsawa etc.
No excuses of promising the customer - you could have just told them you couln't do the top level, and would be back to do them. If you had fallen from that van, there could have been children walking past who could have been injured/killed, as it is you are already illegally parked both on a double yellow and mounting the pavement, and the customer would have footed the prosecution bill and potential claims in compensation for any accidents.
Those who say there is nothing wrong you can see why H&S is becoming such a big thing with working practises like this, there are many injuries, and death from stupid working practises, thinking it will only take 5 mins no harm done.. like to see you say that after you have fallen and broke your back and end up paralysed for the rest of your life, or even killed someone - if you want to practise bad working methods, then you will have to ive with yourself.. personally id rather say sorry i cant do that and walk on..
Totally agree with pingu, you have brought this on yourself by practising extremely stupid work methods.
To many people see the green £££ sounds, rather than looking out for not only their own safety but others around them, and how accidents effect others especially the closes to those involved in any accident.
as eclipse said, you look very professional with a nice van, site, uniform, and you have let only yourself and your reputation down by some silly thinking.