Self-Assessment Refund

In August I was notified I was due for a refund. I requested only a partial refund directly to my bank account, which was processed in 10 working days. However, I now see that the rest of the amount has been sent to me via cheque. First of all why is that? And most importantly - I haven't received the cheque yet, and it's been over a month now. My address is up to date, so I doubt that's the problem,

Hi,
 

I would not be able to confirm the reason for this without viewing your account, you will need to contact our Self Assessment helpline : Self Assessment: general enquiries   . Thank you.