3TB Fusion Drive; hard drive and SSD In one enclosure or two separate enclosures

They should not need the SSD in order to recover data from the HDD. Anyone charging €1107 for data recovery should know this.

A Fusion drive consists of a relatively small SSD + a larger HDD. They are both inside your iMac but they are separate components. The SSD component only acts as a sort of cache for the HDD; only the most frequently accessed files are stored on the SSD and even then only temporarily because "frequently used files" change all the time; and most of what is normally on the SSD are system files. Nearly all your data files are stored on the HDD, and there is nothing special about them that "requires" the SSD to be present.

Regarding the SSD, yes it is inside your iMac. Once you got your iMac repaired with a new HDD and reinstalled macOS, everything on the SSD & HDD would have been erased during the installation.

Don't they have the fusion drive? A fusion drive are a ssd and hdd in one so they must have the ssd when having the fusion drive

True enough, but even though it's a single logical volume most of the actual data files will be on the HDD. A good recovery service should be able to recover most of what's on the HDD.

Re: “The SSD component only acts as a sort of cache for the HDD”

Part of the SSD is used as a write cache until the Mac determines where it wants to store the data. But data is spread across the HDD and the SSD. Either by itself is only part of the logical volume created by the Fusion Dtive software in macOS.

The SSD component of a Fusion Drive is not a physical part of the hard drive (the way that a SSD cache would be part of a “hybrid” drive).

Opening the HDD will not reveal a SSD but may damage the HDD further.

An Apple Fusion drive is a virtual drive configuration that consists of two separate physical drives: A larger HDD, and a smaller SSD. These two drives are what are installed in some Mac models. These were an option at the time when large capacity SSDs were very expensive. They are no longer offered by Apple.

On the other hand, as Servant of Cats has mentioned, a similar type drive, called a hybrid drive does consist of a single physical drive that has both the HDD & SSD components together. AFAIK, Apple did not use these types of drives as "Fusion drives."

An Apple Fusion Drive is made up of an SSD & an HDD. The SSD is not part of the HDD. The SSD is connected to the iMac logic board. The HDD is also connected to the logic board. The two of them are 'merged' virtually (that is, via software) so they act as a single drive.

If your repair man replaced the HDD, he left the original SSD in your iMac and used terminal commands to do what is called "resetting the fusion drive" which is the software process by which the SSD & HDD are interrelated to each other to act as a single 'fusion drive.'

There is no SSD card inside the HDD; and you do not have 2 SSD cards in your iMac.