IDP app used but received email from home office to book the appointment before 10th Aug

[ssn_1981]

Hello Sir,

I have applied for Neutralisation in UK after my ILR+ 1 year in June.
already used IDP on 21st July but received email two days before from home office stating I have still not booked my appointment and need to do the same before 10th August.

Online UKVCAS account shows Your supporting information has been sent to UKVI also contacted them 2 days before.
They sent supporting information again yesterday and asked me to contact home office on 03007906268.

I tried lot of options but not able to contact home office.
Can you help me how i can contact home office to ensure they received my documents?

Is there need to book appointment before 10th August ( paid only now due to unavailability of free appointments before 10th august )?

Please suggest.

Thanks in advance.
Snehal

[AmazonianX]

See below

british-citizenship/naturalisation-appl ... l#p2083850