This is a common first users issue they may stumble across when trying to submit quotes on transport jobs.
When placing a quote ensure you are not using the £ sign when entering the value, to place a quote you just need to enter a numeric value such as 200 or 300 and not try using a currency sign.
Number input is also disabled in the message field when submitting the quote, this is to ensure no one breaches the rules. Try to keep your message attached to your quote as short as possible, many customers do not like lots of junk text to read.
