Error 403 occurs when you have been denied access to our systems due to less than satisfactory API behaviour. The most common example is when you exceed your rate limit by spamming the API with too many requests in a given time frame - for example, if you are submitting an invalid order, or your internet connection is weak and was thus attempting too many re-connections.
Information regarding the specific error you were encountering is contained in your logs. Please be careful in the future as continued abuse will lead to increasingly more severe bans.
If you are still experiencing this error after 1 hour, please send us your IP address and we will investigate further.