Martin Lewis, founder of MoneySavingExpert.com, advised households on their supplier’s standard tariff to submit meter readings today, before the energy price cap goes up tomorrow.

Ofgem announced in February that the new price cap will be £1,971 from 1 April, up from the current level of £1,277, piling on the pressure to people already struggling with soaring inflation and rising petrol costs.

Lewis said in a YouTube video: “Before we get to 1 April, preferably on the 31 March, do a meter reading and send it to the company. Why? Because then you are drawing a line in the sand that says to them: ‘All the energy I have used until this point should be charged at the cheap rate. Do not estimate my usage, I am locking it down so you cannot charge me any more than the amount I’ve actually used from 1 April onwards’.

“Some people might be saying: ‘Why don’t I make that just a little bit higher than it really is, so some of my April usage would be at the cheap March rate?’ Well, the answer is because that’s fraud, so don’t do it.”

But the number of people following Lewis’ advice has caused energy suppliers’ websites to buckle under the pressure. According to DownDetector, British Gas, Scottish Power, E.ON, SSE and Bulb all have website issues today.

Customers took to social media to complain. One British Gas customer Tweeted: “Is everyone in the country trying to get into their British Gas account right now or have they purposefully broken their website so we can’t update meter readings?”

Scottish Power’s Twitter team admitted the company was having website issues and advised customers to submit meter readings over the phone; while a message on EDF Energy’s website said it was “carrying out essential maintenance work”.

E.ON went so far as to blame Lewis for it’s website not being able to cope, with the @E.ON Next Twitter handle Tweeting: “Unfortunately the website and phone lines of every supplier are being hammered today. Martin has once again created unprecedented demand bringing down Britain.”

Some billpayers may be thinking of cancelling their direct debits to energy suppliers in order to have more control over what they pay, and amid fears that suppliers are upping direct debits by more than necessary to improve their cashflow.

But ditching direct debit payments in order to pay for energy when you receive your quarterly bill will cost you more. The quoted energy price cap of £1,971 is for energy customers who pay by direct debit – those who pay on receipt of the bill have a price cap of £2,100 for typical use, about 6% more.

The price cap for prepayment customers is £2,017 a year. So direct debit is still the cheapest way to pay for energy.

Justina Miltienyte, head of policy at Uswitch.com, said: “If you do not have a smart meter, it is important to take and submit your meter readings before 1st April to provide a concrete record for you and your provider of how much energy was used prior to the price rise, and to avoid them estimating your usage.

“As the hours tick down towards the jump in energy prices, thousands of people have been trying to give their supplier a meter reading to ensure they don’t pay any more than they need to.

“Several suppliers seem to be struggling to cope with the deluge of meter readings, and we’ve had reports of some providers’ websites being unable to accept readings or even let customers log in.

“If you’re unable to submit your meter reading online right now, don’t panic as website issues are often temporary. Try again later today or take a photo of your reading with a date stamp visible in the image as evidence. Your supplier may offer other ways to submit readings, so have a look at the recent communications they’ve sent you to find further details.”