Help Assistant not accepting valid phone number on form

[#1]

Is there a glitch on the Help Assistant page, as it keeps refusing my ticket as says Mobile Phone No is not valid.
It is!
I have tried a gap between first (07473) & second part of number, makes no difference

[#2]

Hi Gel,
I've just sent you a PM regarding this matter. I'll await your response

[#3]

Done