I read there are copyright registration services to whom you can send your work to be protected and they would document it, save it in their servers, and in case when needed will send you a formal proof so you can use it in court. Some of these services also offer monitoring websites for violation of your IP, and some do takedown services. There are some which are expensive, so for that price I prefer registering in the USA copyright office. Nevertheless:
1. There is an affordable one https://copyrighthouse.org which costs at this time of writing 99 pounds (one time pay) for 100 registrations for unlimited time. Seems reasonable. Anyone can shed some light on this company (how big they are ? what is their reputation ? how long are they doing this service ?) ?
2. Can you recommend on other affordable services that have good reputation?
I also was going to ask about https://www.copyrighted.com which few days ago was as I remember about 100 Dollars (one time pay) for unlimited registrations for unlimited time, but strangely now has changed to a monthly subscription – so I guess this option is now ruled out for me.
It really depends on which part of the service you value the most. If you are based in the USA or that is the market where you think it is most likely you may need to defend your intellectual property, then registering with the Copyright Office will provide all the protection you need as far as being able to bring a claim in the courts there is concerned, but obviously that won't get you any ancilliary services such as pro-actively searching for infringing use of your work. For that you would need to use one of the many agencies which specialise in that field. But be aware that they may charge a fairly large proportion of anything they may recover on your behalf. And they tend to specialise in particular areas of copyright works, such as music or photographs, rather than, say, literary works or artistic works, and generally only search for infringement on the internet rather than, for instance, in print media.
You also need to be aware that paying an agency just for registration services is not a universal panacea. Registering a work (even with the US Copyright Office*) does not, prima facie, establish that you are the author of the work. It merely shows that at a particular point in time you had possession of the work or a copy of it. In many cases of copyrght infringement, ownership of the copyright in the work is not in dispute, and it is more likely that a defence of independent creation or fair use will be run, which doesn't need evidence from the copyright owner to establish the veracity of their claim to ownership. And of course you need to remember that registration doesn't prove that copyright actually exists in a particular work in the first place. For example, whether the work is 'original' enough to qualify for copyright.
I can't recommend any of these services as I have never used them.
*The Copyright Office have themselves admitted this recently over the disputed attempt to register copyright in the original bitcoin white paper