Stay away from Gusto

Here's a timeline of an unresolved issue with an employee's FICA taxes:

10/5 Chat - asked me to email
10/5 Emailed
10/10 No response. Chased for a response
10/13 Got a response with a suggested fix. Did not work.
10/13 Replied back asking for a fix.
10/19 No response. Chased for a response.
10/19 Chat - issue escalated.
10/25 No response. Chased for a response.
10/26 A fix applied from the backend but the calculations are now all over the place because of the said backend fix. Called straight after receiving the email. Was told to email them back as phone cannot handle my request (they did screen share).

Today is now start of November and unable to pay the said employee because of this issue.

The Gusto customer service is non-existent. The phone help (I always connect to someone offshore maybe Philippines from their accents) is an extension of online FAQs, nothing substantial. Please suggest how to approach and get a response from the team other than constantly emailing them?
For anyone else, avoid at all costs.