Hello everyone,I wanted to give an update on what happened with this. A builder friend of mine had a go at removing the scratch to no avail. It was looking like £180 approx to replace the glass from the conservatory company. My mate managed to find the same bit of glass from a local trade supplier for only £60. I bit the bullet and replaced the glass. Ive kept the customer though they dont want me to clean the conservatory. Im still convinced I didnt scratch it but whatever its sorted now and im over it. Ive learnt alot from the experience too. For any new window cleaners I'd offer the following advice:1) When taking on a new job, look at the condition of the windows. If they are heavily soiled/paticularly with cement etc inform the customer that cleaning the windows may show up scratches already there or the cement render can cause scractches when removed. That way they cant really blame you if something goes wrong.2) If really in doubt about a job, dont take it on. Theres too much work out there to worry about one difficult job.3) Be honest. If youve made a mistake, be honest and put it right.4) Use soap and water when using a scraper just to be 100% safe.5) If accused of scratching the way you respond initially has a massive impact on the result. In my case because im a new window cleaner when this customer said id scarcthed the window i assumed i must off and thus handed the power to the customer. In 99% of cases you wouldnt have done it. Be firm and explain how its virtually impossible, unless of course you did do it!6) If you need to replace glass, get a trade price from a glass supplier not a conservatory company who will want to make big profit on it. 7) Have a glass waiver that you can ask the customer to sign if the job looks tricky. (there are a few knocking around on this forum) Trust no one. Im convinced that my customers husband scrached the glass and has lied to his wife and me. 9) Stuff will go wrong. Dont let it get to you. It could be a scratched bit of glass or a broken garden knome, your lifes bigger than that, try not to strress.10) If you rush jobs this can lead to more accidents, so try and find a balance between efficient working and safety.Cheers,Calebps thanks for all the help and advice from the other posters.