I feel your pain. It’s a terrible situation to be in.
A few suggestions: Firstly, are any of your tenants eligible for programs such as SCRIE or DRIE? If so, this may help with cash flow as partial payments will come from outside sources. I would put up notices in the foyer, have an information evening and send out information pamphlets to tenants. Having this in place will also help with rent increases down the track.
Secondly, for those who won't pay, I'd make a very strict 2 month arrears policy and find a good non-payment lawyer. Every two months they are behind take them to court. Each and every time. Again, inform tenants of this new, no exceptions policy. After a while many will get sick of having to take the time to go to court and will either move out or start paying more frequently. And often one visible eviction can be enough to let the tenants know you mean business. If that still doesn't work you, at least have a paper trail to enquire if you might have grounds for a holdover further down the track.
Another option for those who aren't paying is to include a list of local charities or numbers of outreach services when sending delinquency notices. Information on one-shot deals can help keep your arrears in check.
Yearly increase: What yearly increase are you instigating? Make sure the new price takes into consideration the arrears.
In terms of repairs, contact your local council to see if there may be any government/non-profit programs that may be available particularly if you have low income renters. You'll be surprised what resources are available or even, who you may meet that can offer great advice in your area.
Re-do your budget based on the percentage loss you're experiencing. It's no good having a budget that has a 5% loss when you're running at 30%. You will definitely have to do some fancy footwork but lower your expectations of what can be achieved in the next six months.
If all else fails, I'm happy to lend you my magic wand!!!!