Betfair Bot repair

Hi, I have a bot that runs on the Betfair free API that has been working for years. It loads the markets from the AUS and UK markets every 4 hours and has been happily running on a server uniterrupted for ages. It stopped working about a week ago with an "API ERROR". The original programmer is no longer on here so I need someone to help repair this. The bot is written in c# and it is the loading sequence that is failing. The same problem happened about a year ago and suddenly went away but this time it has been happening for about a week. I've tried running it on different accounts and different machines but to no avail. I've checked the obvious things (like account locked!) but there doesn't seem to be anything I can see. However that doesn't mean to say I'm not doing something stupid! I'm happy to answer any questions to help the programmer understanding how it works but a quick summary is below:- Bot has a couple of confi screens where you enter username, password and the markets to be loaded. When the bot is started for the first time, it logs in then uploads the specified markets from the free API. There are only a few markets being chosen (AUS horses, UK horses, USA horse and UK dogs). The bot then waits until a set period of time before the race and then places a number of bets based on variables that were put in at the configuration stage. The bot then continues onwards and after 4 hours it reloads the market so that it updates its list of future races. I would also be interested in the winning bidders professional view of the code to see if there are more effecient ways of communicating with the free API as Betfair have limited this to 1000 calls per hour and I would be keen to maximise this useage Thanks