The demise of Ovivo Mobile on 19 March has prompted speculation the company ran out of money and fell out with its partners.
The network ran on the premise that users could get free calls, text and data in exchange for being targeted with ads.
A 20 sign-up fee included 15 credit for calls and texts once a customer exceeded their allowance, and extra credit could also be purchased.
The company's revenue model relied on customers using high levels of data via their browser, which would display an advert every ten minutes.
Ovivo used Vodafone's network via MVNO aggregator Cognatel. Mobile News revealed yesterday the firm was involved in a dispute about software with the aggregator, speculating this was the reason its services were turned off.
The website also claimed Ovivo Mobile had been withholding cash from the Vodafone MVNA because of the dispute, which led to the plug being pulled on its services.
This is yet to be confirmed by Cognatel and Vodafone.
The company raised much of its initial funding via crowdfunding website CrowdCube.
The company's director Luke Lang told The Guardian: "We're extremely disappointed that Ovivo Mobile has had to announce that for reasons beyond their control, it is closing down. When Ovivo raised finance through our site the company was in a good position with 10,000 customers and an experienced management team.
"However, the mobile industry is a highly competitive marketplace that is challenging for even established players, particularly during difficult economic times."
Unsurprisingly, Ovivo customers expressed their dismay at the company's demise. One user on the Hot UK Deals forum said: "Totally shocking. No notice whatsoever. At least they're issuing PAC codes but still to give zero notice is really bad. I just did not see this coming."
Meanwhile, another said: "Not happy about this. Going out of business is unavoidable sometimes but to do it this way is unforgivable. This has left my girlfriend without a phone to use in the case of an emergency."
This forum user said the company kept increasing the amount of free data and it could have been this that led to the company closing down.
"That is appalling... so they had NO IDEA it was going to happen, no notice no nothing... . So why did they keep putting the free data up and up when they must have know things were going south?"
The company reportedly sold its 50,000th SIM card in January and was hoping to raise revenues of 3m in 2014.
