Citizens Advice has called for the compensation system in the broadband market to be overhauled, as it is "deeply unfair" to consumers.
According to the organisation, Openreach typically compensates suppliers for each day that there is a delay fixing a landline fault or setting up a new landline or broadband connection.
However, Citizens Advice has pointed out that customers who have been inconvenienced do not get anything to compensate for their losses.
Indeed, it stated that whereas suppliers get compensated automatically, customers have to "fight for a payout".
Citizens Advice has therefore called on MPs to address this imbalance and back a clause in the Digital Economy Bill giving Ofcom the power to introduce automatic compensation for consumers.
The organisation has also urged Ofcom to set clear standards on when people would be entitled to compensation and how much they would receive.
This, it said, could be similar to the system used in the energy sector, which sees providers pay out £75 if electricity customers are still disconnected 12 hours after a power cut.
Gillian Guy, Chief Executive of Citizens Advice, commented: "Companies are paid every time a broadband or landline repair or installation is delayed.
"But customers who bear the brunt of these problems have to fight for compensation from their broadband company - and may not get any.
"When installations or repairs are delayed this can leave broadband customers without an internet connection for days."
Ms Guy added that the Digital Economy Bill offers MPs an opportunity to ensure broadband customers affected by delays do not have to negotiate and fight for compensation.
"It is important that clear standards are set for this compensation so people know exactly when they are eligible and how much they can claim," she said.
According to figures from Citizens Advice, 20 per cent of repairs carried out by Openreach were not completed on time between April and September, along with six per cent of installations.
The organisation said this means an average of 14,000 households and small businesses waited longer than they should have for repairs to broadband and phone lines, while a further 11,000 experienced late installations.
Earlier this year, Ofcom opened a consultation on the idea of automatically compensating consumers and smaller businesses if the service they receive from their broadband provider falls below expectations.
The watchdog is using the findings to inform potential future proposals for new rules on automatic compensation, which would "protect consumers from the negative impacts that service quality problems can cause" and "incentivise providers to deliver to higher standards".
The idea was subsequently criticised by Vodafone, which said implementing the measure could lead to broadband companies having to "sacrifice service quality in order to invest in compliance measures".
SSE was equally critical, saying it is "totally unacceptable" to design a compensation system for network and wholesale issues that does "not directly entail network and wholesale communications providers having to pay out the principal compensation amounts".
This suggests that the industry could lobby for BT's infrastructure subsidiary Openreach and other operators of underlying infrastructure to pay out in the event of a loss of service.