As long as you have the playHT API Key attached to your VAPI account, you can update the assistant id through the documentation page as a workaround. Use your VAPI API key as the bearer token, id field is for assistant id that you want to add the voice to, and use the dropdown menus to select voice then playHT as the provider, then enter your voice id into the voiceId field. If you would like assistance with this, we can walk you through it. Below is the link to the documentation where you can update your assistant:
For the other 11labs issue, could you please share a loom screen recording of the issue? We would like to investigate this and reproduce it with the same steps on our end.