How do you get more server time for Zoho Crm to process functions?

How do you get more server time for Zoho Crm to process functions?

We're having some serious function problems within Zoho CRM.  Our customer base has doubled over the last few months, and functions and automations that worked 100% well before with less customers/ automation calls,  now randomly fail.

Generally if I manually process the functions on a view, they will mostly work, but if called by a workflow based off a time event, or a field update event, only 200 or so calls will be made rather than the 5000 we need.
When the functions fail, if we manually re-run them from the function failure section, they work fine.  They don't rely on dynamic data, so it is simply a Zoho server scheduling issue - the function is being failed because we are requesting too much server time on our single site

The other more insidious problem is that an individual "if" statement within a function might fail to evaluate, due to server overload,  so a section of a function fails, but the rest of the function passes, so doesn't appear as a failure.

We've tried scheduling, splitting functions etc, but currently the only way out of it has been for us to employ a tech to manually simulate our workflow automations, and double verify the functions work.  This is obviously a stupid waste of time, and I'm now costing migrating from Zoho.

Has anybody else met this?  I've asked Zoho sales and tech support for assistance multiple times, but I'm getting nowhere.  I'm happy to pay for extra server time, but I need our automation to work 100%