What to do if the appeal is rejected from the high court

My father has been convicted in CBI Trial Court, for 4 years term. He worked in a PSU Bank, and is convicted for forging loan documents to farmers. Now we need to apply for suspension of sentence in High Court Chandigarh, in order to get him on bail,. Kindly advice on the time taken for the same, and the surety of getting the bail from High Court, as my father was only the signing authority of the branch, and the documents were forged by the clerk and Patwari. Both of them have also been given a term of 4 years by the trial court. Kindly confirm if we can get my father out of jail, and what would be the time frame for the same.. Pls help, as my father is a senior citizen with diabetes problem. He is innocent and has not gotten involved in any such matter. Some of the loan amount has already been returned to the bank by farmers. They were sentenced for 3 years term, but got immediate bail from the trial court. Kindly, also share any other issue we should be aware of.