Unfortunately the Discretionary Housing Payments are just that - Discretionary.
They are usually only granted for a limited time to help the applicant through a particular difficulty.
There is a limited fund at the councils disposal and they have to share it out as they see fit.
If you are not sucessful in your application there is no appeal.
It seems a bit odd in your post that you do not mention
Housing Benefit, have you claimed this?
As a single person in private accomodation you would be claiming the 'Shared Accommodation' rate.
The 'Shared Accommodation' rate in Glasgow is £68.28 a week.
This would mean you still had to find about £22 a week to meet your rent of £390/month.
https://glasgow.gov.uk/index.aspx?articleid=4189
You also do not mention claiming a
Council Tax Reduction, have you claimed this?
If you are living in a HMO (1 room in a shared house) then you probably don't pay Council Tax, the landlord will be liable.
Take a look at this webpage from Glasgow Council.
https://glasgow.gov.uk/index.aspx?articleid=3834
There is a HB/CTR benefit calculator there, put your details into that.
(It doesn't need your name or address at this stage, just what you have coming in and what your rent is).
If you are entitled to any HB or CTR it will tell you at the end, and then has a button to click so that you can make your claim online.