Employer with dubious accounting methods and signatures?

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Employer with sly accounting methods?
On the day I resigned, I verbally told my employer that I ´would hand in my 30 days notice that same day, he then told me I could take the extra paid leave days I had left and leave early. I decided to do so and stated my last date of employment in my resignation letter.

Now that I am gone I have had to wait a long time for my last pay cheque, and I had to call them up every day to ask for it, finally it was there and I really needed the money to pay my rent, so my friend picked up the cheque for me when I couldn't. My friend signed for having received the cheque, clearly stating his name next to his signature. On his way from the office he looked at cheque and gave me a call to check the amount was right, the amount was only a third of my monthly salary. I immediately contacted them to object to the deductions and demanded an explanation in writing and a breakup.
Is my friend's signature seen as forging since he did not try to replicate mine? And should it be the employer's responsibility to keep adeqate book keeping and demaning an original signature from the bearer of the cheque?

Having contacted them to object and find out why they deducted my salary, they now claim that I was aware of the deductions and have authorized them. Basically on the deductions they claim that I am being penalized for leaving the company early.But they were the ones who said that I could avail my remaning paid leave days and leave early! I do not have this on writing but I have the email correspondence when settling the leave days and accrued sick days calculation. And even though we settled this they didn't put in the right amount of leave days in their salary deduction calculation (which is the one that I did not see nor accept).

After a long wait I have finally received the salary breakup letter they claim that I signed, just to find out they have forged my signature on it! This would be a very serious matter, right?

I do not have in writing that I could get my full monthly salary even though I left early, since did not expect them to trick me, but they also neglected to tell me that availing my leave would, according to them be seen as not giving 30 days notice.
I do believe that I have enough evidence against them, for this and a lot of other things - especially with them forging my signature - would this support the point that they tried to trick me by not informing me that availing my paid leave would be seen as 'leaving early' and not respecting the 30 days notice? And the fact that they did not present me with the salary deductions prior to writing out and handing over the cheque?