I love HelpScout. Strongly consider them. Funnel customer experience and success to them.
(no affiliation, just a satisfied customer)
(no affiliation, just a satisfied customer)
Strongly recommend spending ~1 hr exploring HelpScout's multi channel support via their "Inbox" product, no guarantees it solves your problem perfectly, but might save you a bunch of time and get you 80% of the way to your target outcome. Good luck!