This extra line in frequencyfinder.py at around line 562 seems to do the trick for ampersands.
Looks ok as well if no ampersands are present.
Having never written any python code, it needs checking out properly.

Code:
	def saveProviderFile(self):
		customProviderList = []
		self.strongestTransponder = self.transponders_unique[self.iterateUniqueTranspondersBySignalQuality()[-1]]
		for tsidOnidKey in self.iterateUniqueTranspondersBySignalQuality()[::-1]: # iterate in reverse order and select the first system 0 transponder
			transponder = self.transponders_unique[tsidOnidKey]
			if transponder["system"] == 0:
				self.strongestTransponder = transponder
				break
		self.strongestTransponder["network_name"] = self.strongestTransponder["network_name"].replace("&", "and")
		network_name = self.strongestTransponder["network_name"]
		customProviderList.append('<provider>\n')
		customProviderList.append('\t<name>%s terrestrial</name>\n' % network_name)
		customProviderList.append('\t<streamtype>dvbt</streamtype>\n')
Simple1080 skin produces the following warnings in signalfinder…

Code:
<   972.036> [GUISkin] warning, skin is missing element background in <class 'Plugins.SystemPlugins.AutoBouquetsMaker.scanner.frequencyfinder.AutoBouquetsMaker_FrequencyFinder'>
<   972.037> [GUISkin] warning, skin is missing element progress in <class 'Plugins.SystemPlugins.AutoBouquetsMaker.scanner.frequencyfinder.AutoBouquetsMaker_FrequencyFinder'>
<   972.039> [Skin] processing screen SimpleSummary:
<   972.044> [ePNG] couldn't open /usr/lib/enigma2/python/Plugins/SystemPlugins/AutoBouquetsMaker/scanner/images/background.png