James Hardaker was travelling on the 12.15pm East Midlands Railway (EMR) service out on Friday and said he witnessed a number of passengers being turned away.
Another passenger on a train on Saturday said he was also "amazed at how bad the service from EMR is" and feared it threatened the recovery of Skegness.
EMR has told Lincolnshire World that the disruption at the weekend was due to "engineering works on the line" but they have also been struggling to reinstate services impacted by the pandemic.
Last month EMR announced four services between Nottingham and Skegness axed during the pandemic would still not be reinstated until May.
However, Mr Hardaker and another disgruntled passenger are not impressed with the service being offered.
Mr Hardaker contacted our newspaper from his seat on the train. "I'm on the 1215 train out of Skeg and saw that a good number of passengers had to be turned away due to lack of space on the train," he said.
"There are some seats to spare but not enough room for luggage for the dozens of people going home presumably from Butlins.
"With no 1115 train they (EMR) are trying to cram two lots of passengers onto one train which only has two carriages.".
Steve Mason got in touch on Saturday and said that after a £14billion Government investment in the rail industry in the past two years he was not impressed - and not convinced the reason was down to engineering works as claimed.
"There are pre planned works between Grantham and Nottingham but no reason a full service can't run between Grantham and Skeg as advertised," he said. "There were no works on Friday and still trains cancelled .
"Even their (EMR) own website says the cancellations are due to lack of staff as per attachment,
"They have chosen not to run a proper service nor provide sufficient extra carriages or replacement busses.
" I am amazed at how bad the service from EMR is and feel it threatens the recovery of Skegness and the rest of Lincolnshire.
"On a sunny Spring Saturday, they cancelled 10 services to and from Skegness with no replacement - most days they cancel four trains as routine but this is appalling.
"On Friday night, the final one to Grantham was cancelled and with stations unstaffed and most were not replaced by a bus.
"Passengers just get stranded for hours in the cold with no facilities. Skegness station isn't even open for ticket sales today.
"No other company behaves like this on the railways just this one as they know there are no busses to rival them.
"Worse than that they have been given a multi billion bale out by the Government with their fellow companies."