KEEPFILTERS need help

Hello, thank you for your question and time.

In general I need to calculate two conditions in one measure.

First condition:

Always (regardless of filters), only for one department “AA Department” customer ID "5335794105" was excluded from the total results.
How this measure is currently calculated:
Sell-out =
VAR_customer_excl =
CALCULATE (
[Base Measure],
KEEPFILTERS ( NOT ( 'Dataset'[Customer ID] = { "5335794105" } ) )
)
VAR_dep =
SELECTEDVALUE('Dataset'[Departmet])
VAR_default_value = [Base Measure]
VAR Result =
IF ( _dep = "AA Department", _customer_excl, _default_value )
RETURN
Result

But there is an error here, since when selecting several departments, total ignores the condition for excluding the customer ID "5335794105" from the “AA Department”.

Second condition:

If only 2 companies "Fourth Company" and "Fifth Company" were selected at the same time, the volume of "Fifth Company" was multiplied by ExchRate (VAR _exch_rate = 5). Under other conditions in the slicer, the multiplier is not used.
How this measure is currently calculated (this measure works fine.):

Sales with Condition =
VAR_count_check =
DISTINCTCOUNT('Dataset'[Company])
VAR_exch_rate = 5
VAR_c1_value =
CALCULATE (
[Base Measure],
REMOVEFILTERS('Dataset'[Company]),
'Dataset'[Company] = "Fifth Company"
)
VAR _c1_value_mp = _c1_value * _exch_rate
VAR_c2_value =
CALCULATE (
[Base Measure],
REMOVEFILTERS('Dataset'[Company]),
'Dataset'[Company] = "Fourth Company"
)
VAR_default_value =
CALCULATE (
[Base Measure],
REMOVEFILTERS('Dataset'[Company]),
VALUES ( 'Dataset'[Company] )
)
VAR Result =
IF (
CONTAINSROW ( VALUES ( 'Dataset'[Company] ), "Fourth Company" )
&& CONTAINSROW ( VALUES ( 'Dataset'[Company] ), "Fifth Company" )
&& _count_check = 2,
_c1_value_mp + _c2_value,
_default_value
)
RETURN
Result

For the first condition (with customer exclusion):
if one department is selected, totals are correct:

when two or more departments are selected, totals are incorrect: