Houzez wordpress theme correctly configuring

I have a client who has a houzez wordpress theme website, the previous developer failed to complete the configuration. Please look at my clients below issue:

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There are a number of issues with the Houzez theme site that need resolving
technical and visual,

But the most important Issue to be resolved is the Package, Payments, Renewals of, Invoicing accounts, the reason this theme was chosen over other property themes is because of the internal accounts, invoice system that if worked properly could be up scaled and if at some stage there was 100s or even 1000s of payments for packages it would all be automated,

So what needs to work properly before anything else is:

The purchase of any subscription package, by PayPal or Card “ remove BACs “
The issue of Invoice for the package, and issue for each regular subscription, and payment there of,
The regular payment of that subscription until further notice,
The renewal of that package after payment received, With no interruption to service for subscribers just like any other out there.
The automatic mailing out of correct notifications to agents re packages and payment renewals.

Currently, the purchase of any subscription package is possible by PayPal, that works fine for the first purchase of package,
from then on I’m not sure, no one has yet tried to use the stripe payments so don't know if works, so needs testing,
Last time we did a test was December 19 we made it a daily package the payment were received the first time,
and also the second day, and package renewed,

On the third day the payment was received but package was not renewed a package cancellation notice was mailed out
but payment was received,
A Nightmare !

I haven’t run a test since then as so frustrated,

As I had a few people buying packages I have started to renew packages manually as I didn’t want to lose credibility
“ I'm using an excel doc “ again a nightmare and there is less then 10 !

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If you could please provide me with the cost of your fees
for resolving the above issues.