National Car Rental review: customer service at the airport

I reserved a car through my company's business account. I am on travel for business. I rented the vehicle from March 15, 2019 to April 12th, 2019. My travel has been extended to May 1st. I am currently trying to reach the Norfolk International Airport National Car Rental. I have tried getting a hold of National for 2 days now. I am trying to extend my vehicle however I can not reach them. I have spoke to the Customer Service at the National Extensions Department multiple times on extending and they said they cannot extend on their side and that I would have to call the Airport directly to extend longer than 30 days. I have no option to return it to the location due to being gone for travel. I have precisely called the National at Norfolk International Airport 46 times spanning 2 days. I have reached less than twice. First time was when I was told I could extend but they could not do it right then and that I had to call back later. The second time I reached them was through the Enterprise booth next to them in the Airport. Enterprise transferred me to their line. I was on hold for 2 minutes when I heard "Are you still there" and then I proceeded to speak however it was silent on his end. I said hello and then waited 15 more minutes with no avail. I have till Thursday, April 11th to get this resolved and extended. If I do not get this resolved by April 11th, I will return the vehicle at a different location and no longer use national or enterprise. I will go with another company for the forseeable future. I am a frequent traveler and I travel on average of 8 months a year for work. However, I most likely will not use National if this is not resolved. I have never received worse services. Calling a business 46 times is not acceptable. The Customer Service line also called them to no avail and then proceeded to send them an email. I also left multiple voicemails and no resolution. Please contact me for resolution. I am running out of time to renew my National before proceeding to another company. Rental Agreement # [protected] and Telephone #[protected]