How lack of attention/professionalism can constrain your business

I've been trying to purchase a mobile phone from O2 website since last Sunday. Only today I've finally figured out how to complete it. What was the problem? My delivery address was too long but the website didn't say a word about that. Every time I tried I got the same generic error message: "Unfortunately we are currently unable to process your transaction. Please try again later. "  The whole process consists of 5 steps and delivery address is typed during the 2. step and the error appears when the final confirmation button has been pressed. I'm still shocked by the fact that there is not validation of delivery address in terms of its length and that it prevents some users from purchasing.......it's just unbelievable