My HTC phone is defective. It only works when in s...

My HTC phone is defective. It only works when in speaker mode. I have been waiting four months for resolution!
I have contacted HTC nine times: 10/26/17, 11/15/17, 11/24/17, 1/15/18, 2/1/18, 3/12/18 (twice), 3/19/18 (twice).
On 11/15/17, a swap was authorized. HTC was to send me a replacement phone, and a hold was placed on my credit card pending receipt of my defective phone. I never received a replacement phone.
Since that time, HTC has now decided that I must send them my phone first, and wait (for who knows how long, given their current response record to emails and phone calls), for them to send me a replacement phone. This would leave me without any phone until the replacement would arrive. I don t understand why they changed their requirements, without notifying me until I kept contacting them, regarding the status of the replacement phone they supposedly were sending in November. At one point, they told me the phone was on backorder. Then it changed to them requiring me to send them my phone first.
Trying to communicate with this company is very difficult. They respond with scripted answers that do not address my concerns, nor get me a replacement phone. I ve continued to request names and contact information for supervisors, but have been told they cannot provide that information, or that they are the supervisor but are unable to address my concerns. It seems nobody in this company is able to do anything.
I feel they have little, or no, concern for their customers. Their customer service is abysmal. I would NEVER purchase another thing from this company after the way I've been treated!