New Collection with Professional Debt Mgmt - advice needed

[FicoRiRi]

Hi, I recently got a call from PDM regarding a debt from a rental I lived in previously. I owe about $10K. I only just got the letter from them after I already spoke to the rep and paid $1500 for now. I don't know how to dispute the charges and I already paid some of the money so I believe I have to pay the entire amount asap. They are calling me again in another week trying to get the rest of the money. They are threatening to report this to the credit bureaus as a collection. I worked really hard on getting my scores in a really good place. I don't want a collection to go on it and tank my scores which are in the 800 range. I am also afraid of my scores getting lowered resulting in adverse reactions from the credit cards I do have. I asked about a payment plan but unless I pay the full amount they will report it to the credit bureaus. What are my options? It will take me another month or so to get the rest of the money. My only options are:

1. getting a new credit card with a 0% balance transfer

2. personal loan at 9% APR 

3. withdraw money from 401K ( 20% goes to the IRS).

Any advice on what I should do to navigate this? I am not working at the moment (was laid off and have serious medical issues I am recovering from) and this debt is coming at the worst time. 

Thanks!

[FireMedic1]

Sounds like they are pushing the issue to PIF or report. Tell them the situation your in. Work out a payment plan to not have it report. Since you made a payment. That reset the SOL as it is. If the plan can be put into place. Then PIF as you stated you can when the time comes.

[FicoRiRi]

Thank you @FireMedic1! I will try to get a payment plan but my previous attempt to do so did not work. I wish there was a script of things to say. I mentioned I am not working but that did not help matters. There are programs I have applied to that will provide $ to help pay this off but it takes time to get approved and the rep keeps threatening to report it to the credit bureaus. How do I get more time? 

[FireMedic1]

Tell them the truth. Your money is coming. Just need more time. Until then please let me pay anything till then. Throw it back at them. Cant squeeze money out of a rock.