I created a vapi agent who should supposedly speak in both english and spanish. However, I am unable to get it to work. I need both the transcription and the voice. Right now none of them are taking any inputs. Kindly advice.

Use a multilingual transcriber like Deepgram or Whisper, set a compatible voice, update the assistant prompt to handle both languages, and fine tune speech setting, then test both languages to ensure transcription and voice work properly..