Pathetic time management (no reply for 16 days)

I have not received a response to my debit card dispute since 27 March. That is ridiculous time management and incompetence. On 6 April, I sent a follow-up email to no avail. On 9 April, I sent YET ANOTHER follow-up email requesting a response by the end of business on 12 April - TO NO AVAIL ONCE AGAIN. Please do not call me to tell me you are getting someone to resolve this; I want my dispute escalated to Visa. Thanks.