It's sad, but many employers simply don't want to be "given a chance to make it right". Other than any negotiation when you first join, they want to dictate the terms and then they want you to take it or leave it. Most employer do not want your conditions of employment to be a conversation or a negotiation, and by sticking this change on you without consultation they've acted precisely in order to avoid it becoming one. This is a strong indicator that your employer holds to that approach.
Only if your employer genuinely doesn't realise that you care, and wrongly thinks it was an insignificant change for you, is raising the issue likely to result in them hustling to make it right. If they knew in advance they were making it wrong, then most likely they're already braced for impact.
If your employer is expecting dissent, then literally the only meaningful way for you to express that you're unhappy with the change is to leave (at least, I assume you aren't unionized or you'd mention it: if you were then collective bargaining provides alternative strategies). You can explain to your boss, or anyone else you like, that you now consider the job+conditions+benefits is less good than the job+conditions+benefits used to be. But it won't signify anything because it's the only job they're offering.
If you feel that for some reason your employer is open to negotiating over whether you leave or not, they you could go to them and say "I don't like this, either fix it (and here's my proposal of what I would consider a fix) or else this job is no longer a good one for me and I will leave". But not many employers want to get into this with employees, so unless you know something we don't, the likelihood is that they'll respond, "that's fine, leave". Apart from any other concerns, once they negotiate with you they'll have to negotiate with everyone.
And if they're going to tell you to leave if you can't accept the change, many employers believe that they might well sack you on the spot. So your basic situation (and this is your employer's choice to make it your situation, by doing this without consulting you), is that there's no point bringing it up until you have a new job offer in hand. And once you have a new job offer in hand there's usually no point bringing it up because you're almost always better off just taking the new job than asking them to beat your new offer.
Still, if you're confident that you can get another job, and you don't mind risking a period of unemployment while you look for it, there might be no real harm in giving them a chance. Tell your boss that you're having difficulty with the new arrangements, explain that some extra days vacation or remote-working (or whatever it takes) would solve your difficulty, and see where the conversation goes. Best case they pleasantly surprise you, either by seeing that they've made a mistake or by seeing that you're serious and acting to keep you. Worst case they escort you from the building.