The Welsh Language Society has again protested outside Thomas Cook offices after the travel company said business discussions should be in English.
The largest protest was in Bangor, Gwynedd
About 80 protesters, some wearing so-called Welsh Not signs, gathered at Bangor, where Thomas Cook had told staff of its English language rule.
There were other, smaller, protests at Cardiff and Carmarthen following claims the company had broken the law.
Thomas Cook did not comment on Friday but has previously defended itself.
Those attending Friday's demonstrations were asked to sign a protest letter to be sent to the company.
A number of the protesters were wearing signs around their necks with the letters WN, meaning Welsh Not - a punishment introduced in 19th century schools to stop children speaking Welsh.
The protesters say they will send their letter to Thomas Cook
The letter claimed there was a "level of opposition to your decision to discriminate against Welsh speakers who have been denied the right to speak their own language when doing their work".
The letter goes on: "We call on you to say one small word in your own language - sorry - to your staff, and to the local community, for the disrespect you have shown."
On Monday it had emerged that staff at Thomas Cook's Bangor shop had been asked to use only English to discuss business matters, such as training and team performance.
A spokesman said at the time the company wanted to ensure clear communication at all times and believed English should be used as it is the common language in the UK.